1. Field of the Invention
The present invention relates generally to data communication equipment to be installed at a host computer site, and in particular, with emphasis on an interface connecting equipment to be employed with the associated communication channel and terminal equipment.
2. Description of the Related Art
In conventional data communication equipment intended to accommodate a plurality of communication channels, such units as aggregate MODEMs and aggregate DSUs (Digital Service Units) have been commonly employed. In all of the units exemplified herein, however, MODEM cards or DSU cards to be used with either one of these units have usually consisted of a combination of terminal circuits, each circuit being provided for each individual communication channel or unit of terminal equipment for the purpose of terminating each terminal interface or channel interface, a plurality of these cards being installed in a rack for installation. Incidentally, in the case of a Local Area Network (LAN), terminating circuits provided for the purpose of terminating the communication channel interfaces have sometimes been installed in the LAN router, but terminating circuits provided for the purpose of terminating the terminal interfaces are usually not installed.
Among the kinds of communication channel services considered for inclusion in a communication channel interface are packet services and private digital communication channel services in addition to the conventional private analog communication channel services. There is a very wide range of diverse types of communication channel services provided. Moreover, such novel interfaces as I-series interfaces, LAN interfaces and a variety of other types of interfaces have started to be employed in addition to the conventional V-series and X-series interfaces.
In the case of conventional data communication equipments using aggregate MODEMs or aggregate DSUs, the usual practice is to combine the communication channel and terminal interfaces into one unit and install a plurality of such units in an installation rack. As the result, the combination of the communication channels and the terminals are fixed, and it has therefore been almost impossible to provide different combinations of terminal and communication channel interfaces due to economical considerations. Furthermore, the recent trend in communication equipment, e.g. LAN equipment, has been toward connectionless equipment, and the communication content therefore tends to be full of bursts. Consequently, the use of different combinations of communication channels and terminal interfaces tailored to better meet the needs of each customer and to comply with the amount of traffic becomes all the more important from an economic point of view. Conventional data communication equipment fails to address these needs.